San Francisco 49ers: What to Expect from the Defense in 2015

The San Francisco 49ers have myriad question marks as they head into the summer. One of the questions that must be answered: How good will the pass rush and pass defense perform in the 2015 season?

A strong pass defense starts with a good, consistent pass rush. Putting pressure on the opposing quarterback will help a defensive backfield immensely.

The 49ers have lost Justin Smith and Ray McDonald, two key members of their defensive line. In prior seasons, Smith worked very well with Aldon Smith, as he was able to occupy multiple blockers, enabling Aldon to have fewer blockers to contend with.

Heading into the 2015 season, the most likely replacements for Smith and McDonald are Tank Carradine and Darnell Dockett, who the 49ers signed as a free agent.

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Dockett missed the 2014 season with a torn ACL and, at the age of 34, cannot be expected to play every snap. Expect to see a lot of Tony Jerod-Eddie, and maybe even a little of top draft pick Arik Armstead, as the 49ers will likely rotate their defensive linemen.

Carradine was the 40th overall selection in the 2013 draft but missed the season as he was rehabbing an injury. He appeared in only nine games in 2014 and must prove he can play at the NFL level. Carradine's emergence will be a key for the 49ers defense.

Nose tackles Ian Williams, Glenn Dorsey and Quinton Dial will be utilized in the 49ers base defense but are often removed on passing downs. We will also likely see some of Dorsey and Dial playing at the end positions.

None of the defensive linemen on the current roster are noted for their pass rush, so the pressure will need to come from the outside. Aldon Smith, Ahmad Brooks, Aaron Lynch and Corey Lemonier will be called upon to get to the quarterback.

Smith had his worst season as a pro, generating only two sacks in seven games. His suspension really seemed to throw him off, even after his return. If the 49ers have any hope of competing for a playoff berth, Smith must have a big year.

Playing opposite of Smith, Brooks had six sacks to tie Lynch for most on the team. Lynch emerged as a dynamic athlete and should be even more of a force in 2015. It will be up to defensive coordinator Eric Mangini to find a way to get Smith, Brooks and Lynch on the field at the same time.

The successful return of NaVorro Bowman should also help the 49ers pass defense. Prior to his leg injury, Bowman proved that he is big enough and fast enough to defend the top tight ends in the league.

The biggest area of concern for the San Francisco defense is its cornerback situation. Only two cornerbacks stayed healthy and were also contributors on a regular basis in 2014. Although not superstars, both Chris Culliver and Perrish Cox have moved on via the free-agent market.

There is not a cornerback on the current roster who started a majority of the games last year and stayed healthy. With so many cornerbacks coming off injuries or totally unproven, the cornerback position is a huge question mark for the 49ers.

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Tramaine Brock, a starter in 2013, missed the entire 2014 season with an injury. Jimmie Ward, the 49ers' top draft pick in 2014, was learning the slot corner position when he went down with an injury, costing him the last eight games of the season.

Chris Cook, who was expected to provide depth, also was hurt. 2014 draftees Keith Reaser and Kenneth Acker missed the entire season with injuries. 

Dontae Johnson, rookie cornerback and 129th overall pick in the 2014 draft, started three games toward the end of the season and generally held his own.

The 49ers did sign Shareece Wright as a free agent. He started 27 games for the San Diego Chargers over the past two years. Wright will compete for a starting job this coming season. 

Marcus Cromartie and Leon McFadden provide depth, but to expect more is asking too much.

Trent Baalke, the 49ers general manager, did nothing in the recent draft to bring in a top talent at cornerback. 

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The safety position is one of the few areas of strength for the 49ers. Starters Eric Reid and Antoine Bethea are fine players, with Bethea earning a Pro Bowl berth for his play in 2014.

The 49ers also selected Jaquiski Tartt, a safety out of Samford, with the 46th overall pick in the 2014 draft. Tartt should benefit greatly from the tutelage of Reid and Bethea.

In addition, the 49ers have Craig Dahl to provide depth, and Ward can also slide over to safety if needed.

Injuries decimated the 49ers defense in 2014, but somehow, defensive coordinator Vic Fangio and defensive backs coach Ed Donatell kept the 49ers playing at a high level.

It remains to be seen whether Mangini and new defensive backs coach Tim Lewis will be as successful.

In 2014, the 49ers pass defense was ranked fifth in the league, allowing 220.7 yards per game. They were tied for 21st in sacks, with 36.

Although by employing more blitz packages—the sack total can increase—the 49ers will be hard-pressed to have a better overall pass defense. There are simply too many question marks.

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The 49ers also ranked fifth in the NFL, allowing only 321.4 total yards per game. With so many roster uncertainties, the departure of several quality players and new coaches heading into the 2015 season, look for the 49ers defense to struggle at times. 

Injuries will always play a key role, and that is a fact of life in the NFL. Unfortunately for the 49ers, all of the questions surrounding this team will not be answered positively. Nothing ever goes perfectly in the NFL, and a top-10 defensive ranking is unlikely.

Individual player stats are courtesy of pro-football-reference.com.

Team defense stats courtesy of nfl.com.